1. Field of the Invention
The present invention relates to a method, apparatus, and program for processing images. More specifically, the present invention relates to a method, apparatus, and program for removing line noise components from within images.
2. Description of the Related Art
There are known apparatuses for obtaining image data that represents an image borne by an image carrier. These apparatuses comprise line sensors, which are photoelectric conversion element arrays in which a great number of photoreceptors are arranged in a main scanning direction. Originals, which are image carriers, are relatively moved with respect to the line sensors in a sub scanning direction, which intersects with the main scanning direction. The line sensors detect light emitted from the originals, to obtain the image data that represents the image borne thereby. There are cases in which line noise components (hereinafter, also referred to as “striped blurs”) that extend in the sub scanning direction are present in the image data obtained by this type of apparatus. The noise components are generated due to differences in the properties of each of the photoreceptors that constitute the line sensors. Examples of these properties are gain and temperature properties. In addition, there are cases in which striped blurs that extend in the main scanning direction are present in the image data. These striped blurs are generated by impact shock, which is applied to the line sensors. Therefore, U.S. Patent Laid-Open No. 20030091243 proposes a method, in which image data that represents an image including the striped blur is passed through a filter to extract the striped blur component; and the image data that represents the striped blur component is subtracted from the image data that represents the entirety of the image.
However, there are cases in which there are regions of an image, in which pixel values of the image data that include the striped blur component change drastically. If the above method is applied to these cases, ringing components are generated in the vicinity of these regions during extraction of the striped blur components by filtering the image data. As a result, the ringing components appear as striped blurs in the image, which has been processed to remove the striped blurs. In addition, there is a demand for a process in which linear image information components and striped blurs within an image are separated, and only the striped blurs are removed.